1. Field of the Invention
This invention relates to a method for manufacturing a helium metal vapor laser tube.
2. Description of the Prior Art
The state of the prior art, as to helium cadmium lasers, is exemplified by the article "Simplified Low Noise Helium Cadmium Laser With Segmented Bore" by W. T. Silfvast and L. H. Szeto, Applied Physics Letters, Vol. 19, No. 10, pgs. 445-447, Nov. 15, 1971. That article describes the use of segmented bores to obtain a low noise helium cadmium laser and indicates that when a single cadmium element is used and positioned near the anode, a uniform cadmium density over the entire bore region cannot be obtained through cataphoresis pumping. The article further notes that when instabilities occur near the cadmium source, the instabilities tend to propagate over the entire length of the discharge tube, thereby causing large fluctuations in laser output signals. Based upon these observations, the article recommends the use of a plurality of cadmium elements segmented throughout the bore so as to overcome the fluctuation problem.
In addition, U.S. Pat. No. 3,755,756, entitled "Gaseous Laser Employing A Segmented Discharge Tube" by W. T. Silfvast, generalizes the specific teachings of the above-described article and describes the use of the segmented bore structure to overcome the disadvantages of a single cadmium source.
Other prior art descriptions of helium cadmium lasers are included in articles entitled "Efficient CW Laser Oscillation At 4416.degree.A in Cadmium (II)" by W. T. Silfvast, Applied Physics Letters, Vol. 13, No. 5, pgs. 169-171, Sept. 1, 1968 "Cataphoresis In The Helium Cadmium Laser Discharge Tube" by T. P. Sosnowski, Journal of Applied Physics, Vol. 40, No. 13, pgs. 5138-5144, December 1969, "Discharge Current Noise In Helium Neon Laser And Its Suppression", by Takeo Suzuki, Japanese Journal of Applied Physics, Vol. 9, No. 3, Mar. 1970, "Helium Clean-Up In The Helium-Cadmium Laser Discharge" by T. P. Sosnowski and M. B. Klein, Journal of Quantum Electronics, Vol QE-7, No. 8, August 1971, pgs. 425-426.
The teachings as to helium-cadmium lasers are representative of the state of the art of other helium metal vapor lasers.